[FFmpeg-user] convert from bt601 to bt709

[Bob Maple]

On 6/11/2014 2:58 AM, Rio Kierkels wrote:

> Both of these seem to me to be correct. The EXR is rendered linearly so
> without a power curve and using linear-light RGB tristimulus values.

 [...]

>> It seems like maybe the DPX is either tagged wrong, or some operation
>> happened twice.  If I apply a 'Remove Rec709 Transform' LUT to the DPX,
>> it winds up correct.

> This makes sense as it will do an inverse powerfunction on the image
> leading to a linear waveform readout but an incorrect image as your monitor
> will do that inverse powerfunction again.

Except that I was already working in 709 space.  Yes the EXR is linear,
and was interpreted as such and converted into 709 and looks correct.

The DPX on the other hand was tagged as already being 709, yet I had to
manually "undo" the gamma to get it right in 709, which is why it seems
to me like it was applied twice.  It should have just come in correct to
begin with and look like the EXR snapshot did, if it really was 709.

Bob